Why? Because killer whales can be dangerous. Two years ago, a killer whale named "Tilly" killed a trainer during a show at SeaWorld Orlando, and it wasn't an isolated incident. Tilly had killed people before, not once but twice.

It turns out that killer whales have a long history of harming trainers at SeaWorld. The chain of marine parks was horrified by the death, but it wants to restore the interaction between human and sea creature that made Shamu shows so spectacular for decades.

Last week, SeaWorld lost a battle in its bid to return to the old way of doing things. And it got a firm slap in the form of journalist David Kirby's fascinating and deeply disturbing book "Death at SeaWorld: Shamu and the Dark Side of Killer Whales in Captivity."

In an interview, I talked to Kirby about the inner lives of killer whales, SeaWorld's position and the big questions underlying the debate.

Q: What makes killers whales a unique kind of animal?

A: They are quite possibly the most socially complex animals on earth after humans, and they're among the smartest.

They engage in abstract thinking, recognize themselves in the mirror – which very few animals can do – and understand gestures. If you point your finger, a dolphin [a killer whale is a kind of dolphin] will generally either look or swim in that direction.

They recognize themselves in the mirror, which very few animals do. They can distinguish a Chinook salmon from a coho salmon at a great distance simply by issuing clicks that bounce off the fish.

And they have a great propensity for compassion – for saving each other, for saving other species, for saving people.

Q: What are their personal lives like?

A: They have a highly developed culture. They quite possibly have the greatest family bonds of any animal on earth, including humans.

Males in at least one resident community of the Northwest stay with their mothers for life, and their mothers introduce them to females in other pods.

Ask your mom if she'd like to spend 70 percent of her day, every 24 hours, within one body length of you. I don't think my mom would like it, and I don't think most men would either.

Q: Well, let's just say that you haven't met my mom. But never mind that. What do the mothers get out of this?

A: Part of the deal is that the older males babysit their younger brothers and sisters. Then if the mother wants to go off and rest or get away for a while, mostly to socialize with other females who run these societies, the oldest male will be left behind to watch after his siblings.

Q: Have you talked to guys about these unique killer whale arrangements?

A: I've had more than one Jewish man marvel at the fact that they get to stay home and live with their mother, who introduces them to eligible females. They think that's a pretty good deal.

Q: So these amazing animals exist, and SeaWorld has them do tricks for us?

A: SeaWorld calls them "behaviors." They're tricks: they either don’t do these things in nature or only things that are vaguely similar.

Virtually nothing you see in a Shamu show is anything you’d see a whale doing in the wild, certainly never to blasting music.

Q: Aquariums and water parks have been doing this for decades, right?

A: When the captive whale and dolphin industry got started, they put the animals in tanks, and people would line up to see them. They found that if you got in the water with them and started surfing on them, more people would show up.

So almost from the beginning, it's involved performance and acrobatics.

At the same time, people were protesting at the Seattle Aquarium back in the 1960s when one of the first killer whales was brought in for display. There have been anti-captivity activists since there have been captive killer whales, and their numbers are really growing.

Q: SeaWorld says the killer whale shows are valuable because they educate people about these animals. Is that a valid argument?

A: The most powerful counter-argument is that the education that goes on at SeaWorld is not adequate, especially when it comes to killer whales. The raising of awareness on conservation issues and inspiring people to save their habitat – there’s none of that.

If you walk around SeaWorld, most people are talking about the Shamu whales, but I'm sure most people don't know they're dolphins or where they come from.

My point is that we can argue over whether trainers should be in the water or not, but the big question is whether the killer whales should be in these pools in the first place.

Q: What's the overarching issue here? Are we talking about how we treat animals or how we treat the people who work with them?

A: We're talking about both.

And we're talking about entertainment – I don't think the educational component is very compelling – and spectacle. We're hard-wired to crave spectacular things. We stare at forest fires, we love Broadway shows, we crave spectacle. Look at the Romans and the gladiators.

But in a more subtle way, we're more wired to be compassionate, reject cruelty and be humane. What we have here is a fight between the desire for spectacle and our more humane side.

Killer whales are beautiful animals. When you see them up close, it's really inspiring. But maybe this isn't really what's best for them.

For more about the debate over the captivity of killer whales at SeaWorld, read the Monitor story from 2010 or check my separate interview with Kirby for the Voice of San Diego news organization. He talks about the safety of trainers, the horrific deaths caused by killer whales, and the elaborate precautions that SeaWorld has put into place to protect humans.

To understand the perspective of SeaWorld, read this FAQ about marine mammals from the Alliance of Marine Mammal Parks and Aquariums trade group.